Telephone-exchange system



Mmh 30,1926. 1,578,651

K. M. FETZER v TELEPHONE EXCHANGE SYSTEM Filed Sept. 27, 1924 '7 sheets s'hd 2 Y K. M. FETZER Y -TELEPHONE EXCHANGE SYSTEM Filed Sept. 27. 1924 '7 ShaetsSheef 4 WWW/0r."

Ka/VM fie/zen March 30 1926.

K. M. FETZER TELEPHONE EXCHANGE SYSTEM Filed Sept. 7, 1924- '7 Sheet's' fSheet s 1 March 30 .1926.

K. M. FETZE R TELEPHONE EXCHANGE SYSTEM Sheets-Sheet 7 N a W QNN \NN EL .216: U muzuzouw mot uhno Qz 5.

Smhzcu 2205 v Qmu KKK out ivingthe B o erator agdisconnect;

\ upon thefoperation of a positionalkey and Patented Man 30, i 1926.

UNITED STATE v KARL M. rnrznn, on nnrnnnronn, swimm r megma To w-n's'rnnlv nLncTnIci; COMPANY,,INCORPQRATED, or NEW onx, N. Y.','A coaroaAr ou orunw YORK.

TELEP HoNn-nxonA eE sYsTnrr.

Application filed September 27. 1924. Serial Nb. 7 031 To all whom it may concern:

Be it known that I, KARL MJFETZER, a citizen of the United Statesof America, residing at Rutherford, in the county of'Ber gen, State of New Jersey, have invented certain new and useful Improvements 1n.

Telephone-Exchange Systems, of which the following is a full, clear, concise, and exact description.

instance such calls aretrunked bjineans' of what are termed A and B operatorsor outward" and inward operators. The A or outward operators receive the originating calls and. extend them to t s B or inward operator who" may be located in the" same or in a distant exchange.

An object of the-in ention-is to control the signaling between the fAi and B operators overa commoncircuitf I A second object is to allow the A "or originating .o'p'eratorto change cords with-- signal.

-A third ohjectds to permit team work between adjacentl3 operators case'o ne B operator isrhusy and the adjacent operator idle. In this case'the idle B. operator can take control'of a calling trunk at the first B opera-tors position, .and "extend it to the called line. Signaling between the .B operators, whereby these operators are kept informed that a trunk line has been transferred to another operators position is also an'object of the invention. A; fourth object is to lock out a-B operator who is helping out or handling a call for another B operator, so that'shecanf not receive further calls on her own position until she has disposed of the call she is handling for the other operator.

Afifth object is to release theB? oper ators telephone set from one" trunk line,

panying' drawings wherein:

F 1g. 1 shows the apparatus used in" -This invention relates to improvements in telephone exchangesystems, especially tothose systems employing what is known as straightforward trunking between various common signaling circuit;

ators position. 7

Fig. 7 shows the switchlng' mechanis V to prevent its release from thenextgtrunk line circiiit with which it niayfberconnected.

Othertobjects of the'invention Will he pointed out inthe' following description.

The'mventlon 1s illustrated 1nv the 110001161.-

junction with the common signalingcircuit in connection with an A operatorsposit1on.'

FlgQQ shows the app'aratusat the 'A 1 operators position including a trunk 1 line extending to the B operators position and the timingapparatus. associated With the jcord-clrcuitsffor allowing the A'oper- 'ator to changecords wlthoutjsending adis- 1 connect 'signalto the B operator. V.

Fig. 3 shows the B operators position with-a trunk circuit and controlling .a'ppa-g ratus operating inficonjunction win the Figjl shows theoperators telephone sets rig. 5 shows}: was or he appeals f r I H 70 i v and call sequence circuits fortwo B.operators positions and'the auxillary apparatus Fig. 6- shows the" switching mechanism and apparatus. associated wlth the common signaling circuit located at an A oper- I o and apparatus associated with the common I s gnaling; circuit located at the B oper-" V ators position which operates in synchro- Vnism with theapparatus attheFA"0perat0r's posit1on. V

General method operation,

The straightforward trunk line circuits are arranged to give complete switchhook supervlsion to the outwa-rd operator. Jj The circuits are arranged tostart machine ring- 7mg when thehco'nnection is established and to enable the outward operatorjto rcsriug 1n orderto recallv a subscriber. The trunk clrcuitsfdisclosed herein are arranged to be used with a distributor signaling system, but the use of other signaling arrangements may be readily provided for.

The trunk lines terminate in the outward board in multiple jacks equipped with visual busy signals and at the inward board. in a single cord and plug with associated lamp signal and team key; "The outward operator originating. a call after securing connection with the calling subscriber by means of the answering end of a cord circuit places the calling plug of the cord circuit into the trunk jack of an idle trunk line. This operation causes the busy signals to be displayed and lights the signal lamp at the inward end of the trunk and also connects a tone signal to the trunk line-,-notif ing the outward. operator that the connection is being extended to the in ward operators telephone set.

. At the inward end f thetrunh circuit, the

inward operators telephone set is automatlcally connected in succession to trunk lines on which calls are waiting. When the operators telephone 5813118 connected, the tone signal is disconnected from the trunk line and the outward operator then immedi ately passes the, call. The inward operator completes the connection in the usual manner by placing the trunk plug into the jack of the subscribers line. The inwardoper ators telephone set is disconnected from the trunk lines either when the trunk plug is placed into the line jack of the called subscriber or by the operation of a release key common to the position. Y

The inwardoperator at aposition adjacent to one in which trunk lines terminate may answer on these trunk lines by operating the team key. The purpose of this feature is to allow team work among the inward operators. The adjacent operators telephone set is released from a tollline in the same manner as that of the home operator.

Thetrunk lines are available for other connections as soon as released by the out- 'ward operator if the called subscribers recei-ver is on the switchhook. Provision is made for a delay of 2 seconds before the disconnect signal is transmitted and the vis ual busy signal released, if the outward operator should disconnect while the receiver of the called subscriber is off the switchhook. The reason for this delay is to permit the outward operator to change cord circuits if necessary, for example incase the first cord circuits are defective. The change, if made within 2. seconds is cffected without giving a. disconnect signal to the inward operator. ''After the outward operator secures from the calling subscriber the number of the wanted line, she places the calling plug P into an idle trunk jack J. This completes the circuit of relay 3 as follows: ground,

battery, Winding of relay 2, 100, winding 01 relay 1, 101, P, J, 102, Winding of relay 3 i her left contacts of relay 4, 109, winding of relay 5, 110, contactsof relay 13, to ground. When relay 4 operates it also connects ground to conductor 121 extending to, the signal sequence circuit (Fig, 1) and causes this circuit to function to cause the transmission of a current pulse over conductor 600 (Fig. 6-) and 700 7) to operate relay 701 at the distant end of the trunk line as will be described later. i

The operation of relay 4 connects battery to the winding ofthe busy signal indica ing that its'associated multiple jacks are busy. These signals are held operated after relay 4 releases'as'relay 5- also connects battery t0 the winding of the busy signals. The operation of relay 4 also closes the circuit of relay 7 as follows: ground,battery,

left inner contacts of relay 4, winding of relay 7, 127, contacts of relay 6 to round. The operation of relay 5 opens the circuit which resulted inthe operation of relay 4, but this latter relay remains locked to ground under control of relay 8 through its own contact. I

- .Relaybis. locked to battery through one of its own contacts and-can only be released by the operation of relay 13. The operation of relay 7 disconnects-the grounded rig-ht hand Winding of relay 10 from conductor 125 thereby removing the short circuit around the right hand winding of relay 6.

Returning now to the operation of the signal sequence circuit, when ground was connected to the conductor 121, it caused.

the operation of relay 17 (Fig. 1)., a circuit for which can be traced from ground, outer right alternate contacts of relay 4, conductor 121, winding of relay '17, normal contacts of relays 18 and 19, and the contacts of any other relays between relays 18 and 1.9, as shown. by the broken line to battery and ground. 7

Relay 1? inv operating connects ground at its alternate contacts to energize relays 30 and 31 in an obvious circuit. Relay 31 in operating causes the energizationof relays 501 and 502 (Fig. 5) in the following circuit: I

Ground, outer right. alternate. contacts of relay 4, conductor 121, left alternate contacts of relay 31, conductor 32, right hand Winding of relay 1 501,- conductor 503 and winding of relay"502 tobatteryfl I 1 7 Relay 502 in operating grounds the ST lead extending through relay 601 to battery,

which relay-energizes and in closing its al Which can be traced from battery through theyvinding of magnet 604, alternateconta'cts of relay 602, segment 605 of the trans- .mitte'r distributor TRANSfbrush arm 606 and the groundedinner segment of the distributor. a

Magnet-604 in attracting ts armature releases brush arm 606, which starts revolving in a' clockwise direction; Wheri the brush ing of relay 610 to ground.

- 607, brush arm 7 05 or the receiving distribuarm starts to revolve theo'uterbru shes break 1 contact with segment 611, t iereby "opening the normally closed circuit ot relay 610, the

energizingcircuit irons which can terraced from battery over segment 609 .otthe trans mitting distributor, brush-arm 606 and its brushes, segment 611, lead 613, and the Wind- When relay 610 deenergmethits armature opened its alternate ortro'nt contactsand causedrelay 701 (Fig 7i) atth e distant end; of the line to release,1wh1,ch relay is normal- 1v *operated due to, the normally operated;

cbndition otrel'ay 610.

Relay 701'in releasingconnects ground at its alternate contacts over lead 702tosegment 7 03 of the receiving distributonBEC', thereby causing release magnet 704 to attract its armature and release brush arm 705, which at once starts to'r'evolve in a clockwise 'direction in substantial synchr' o- 'msm With the transmittlng dlstributor. I

7 'When the brush arm 606 reaches segment 607 it connect-s batter standindon se -ment 609 to lead 608, thereby..causing'thereenergizatio'n of relay 610 in thefollowlng circuit: battery, segment 609, brush arm 606,

se ment 607,,lead 608,-contacts of relay 501, leads 504 and 505] and the winding ot'relay 610 to ground.

Relay 610 in operating reconnects, battery at its alternate contacts to lead 600, thereby causing relay 701 at the distant end toloperate, which connects ground over. lead 706 to segment 707 of thereceiving distributor. As before mentioned, the transmitting and receiving distributors rotate .in' substantial 'synchronlsm and, therefore, during- 'the period the brush .arm 6060f thetransmit ter has its brushes in contact Withsegm'ent 1301*.Wlll bring its brushes into contactfwith segment 7 08, therebycompleting a "CHCllll? for the operation of relay-"709 wl .icl i; ..ca n

indi ng or circuit.

tive locking battery.

betraced from battery 710, winding of relay 709, segment 708, outer-brushes o'it brushrarm 7 05, segment 707, conductor 706qand normaloont'actsoi' relay 7 01-to ground.

When relay-709 operates, it loclgsitselttby mcanslotits right Winding and inner-karma ture contactstoground on segment 711', over segment 712' and the lnner brushes of brush arm 7 05, whlch locking'circult' Wlll'bfi main-' tained closed until the brush arm 705 leaves segment 711 near-the completion of the ret o" lution, I

When relay 709,- operated, it --conne'cted ground atxits outer armature-contactsto conductor .713, thereby causing theoperation otrelays'714, 7'15, 716 and 7 in an obvious Relay 7 for the operation of relay/.39 associated with the inner endfotthei conductor (Fig.6),

which, circuittvvil-l be.closed When the brush (14 in operating prepares a circuit arm of. the receiving distributor bridges 's'egments 7 1 8 and-7 19., The circuit thus completedzcan be traced :trom negative battery over conductor 720, normalrontacts ofr'elay 7 21', segment 718, outer brushes of brush arm 705,'segmei1t 719, outer, normal contacts of relay 722, lower normal contacts of relay 7 2S,"loWer normal contacts of relay 724, lower alternate contacts of relay 714, uppernormal :contacts of relay 7 26, conduct-or725 and left .hand. Winding of relay39 togroundfwhich Arelay'. in. operating locksfitselt at itsright hand alternateicontactssto battery. 3

It'should'be noted; that the Windings ot relay 39 are so. connecte'dflthat thenegative' locking 1 battery "aids, the negative ,7 battery supplied'athrough the left hand Winding whereby the relay remains operatedatter" the operating pulse cea'ses,.whereas a'p'ositive operating pulse would have mornentari 'ly operated the relay'but it could not haye locked as itswould have opposed thenega- 1 As none or theother "chain'relays tllig. 5') were operated by the seizure oft-he trunk line,.shown in Fig. 2, none of the other four outer segments 614, 615,616- and 617 of the transmitting distributor will affect relay'610 and, therefore,'its armatures )vill retract as soon as the outer brushes 50f brush arm r606 leave segment 607 and will remain in its retracted position until the brushes contactwith-segment 611, at Whichtime relay 610 Wlll again energlzeto cause the reenergizationof relay 701, Which as before mentioned, is the normal conditionof these relays.

"VJ hen the inner brushes'of brush arm contact it prepared an energizing circuit for relay 619 wlnch can be'traced from-battery, through the, Winding'otrelay 603, left alterl- 606* *made contact With seg1nent618, an obvious [energizing circuit-was completed for relay .Whenrelay 608 closedlits left alternate as previously mentioned.

to ground on the ST lead.

Relay 619 did not operate in this circuit, however, as its winding was shunted by ground on segment 6-18 of the distributor, When the brush arm 606, however, in completing its revolution moved 06 segment 618, this short circuit was removed from relay 619, and, tl 1erefore,

this relay operated in the circuit previously traced.

The operation of relay 619 completes anei'iergizing circuit for relay 8 (Fig. 2), which can be traced from battery, winding of relay 8, conductor 122, right hand alternate con tacts of relay 31, 1), conductor 33, alternate contacts of relay 619, conductor 620, alternate contacts of relay 601 to ground on the ST lead, which is supplied at the 602 opens the circuit-for the start magnet. 604, WlllGlI therefore, releases its armature,

which takes up a position to stop the brush arm 606, when it has completed its revolution. All relays associated with the transmitting distributor are nowin normal position and in readiness to transmit another signal.

The release of relay 4 (Fig. 1), which re moves the ground fromconductor 121', preye-nts further transmission of signals until further changes occur at the outward end of the trunk circuits The operation of relay 39 (Fig. 3) at the inward end of the trunk completes the circuit of relay 60'as'follows; ground, battery, contacts of relay 39, contacts of relay 40, 179, winding of relay 60', contacts of relay 56 to ground. v

The operation of relay 39 completes the circuit of thesig'na'l lamp Q as follows: ground, battery, contacts of relay39, 170 contacts of relay 46, 172, 173, contacts of relay 47, 174, contacts of relay 43, 17 6, cont acts of relay 47, 177, contacts of relay 46, 1'78, lamp Q to ground. The" lighting of this lamp notifies the inward operator of the call.

The operation of relay 39 also completes the circuit of relay 41 as follows? ground,

,7 battery, contacts of relay 39, 170, contacts of relay 46, 172, 173, contacts of relay 47,

' 174*, contacts of relay 43, 17 5,windi ng of relay 41 to ground. The operation of relay 41 connects tone to the'tip. and ring conductors 134 and 135 of the trunk, thus indicating to theoutward operator that the Signal has been transmitted to the inward operators position.

The operation of relay 39 also completes the circuit of relay 42 as follows: ground, battery, contacts of relay 39, 170, contacts of relay 46, 172, 173, contacts of relay 47, 174, right hand winding of relay 42 to ground. The operation of relay 42 connects ground from relay (Fig. 4) and conductor 190 over conductor 189 to the call sequence circuit whichincludes relay 72 thereby causing the connection of theoperators telephone set to the selected trunk. Theoperation of relay 42 also transfers one terminal of its left hand winding from ground to conductor 196. The reason for this connection will be later explained. e V

The operation of relay 42 as above mentione'd, closes the circuit of relay 72 as folljows: ground,contacts of relay 70, 190, con

tacts of relay 42, 189, winding of relay 72,,

contacts of relay 76,184, contacts of relay v75, 185, battery to ground.

When there are no calls awaiting on other trunks ground is connected to relay-'43 as follows: ground, contacts of relay 71, alternate contacts of relay 72, 182, winding of relay 43 to battery. The operation of relay 43: opensthe circuit of relay 41, thereby releasingit, which disconnects the tone' signal from the tip and ring conductors notifying the outward operator that the inward operator 1S connected to'the' trunkand is in position to receive the order. Relay 41 at the same time connects the tip and ring conductors 134, 135 of the trunk to conductors 136 and 137.

The operation of relay 43 also connects the tip and ring of the No. 1 operator3s telephone set to conductors 136 and 1 37 thus completing a connection with thetrunk so the inward operator may converse with the the outward operator. I

Relay 42 is slowv in op'erain'g while relay 41 is slow. in releasing. insures that the tone signal is connected to the toll trunk for a sutlicient length of time to give the full signals to the outward operator.

The combination The operation of relay 43 also disconnects frequency indicating to the inward operator to which trunk circuit her telephone set is connected. V

The operation of relax .43, also connects battery to the lefthand; winding of relay 42 ground thus causing this relay to operate when the receiving distributor 622 bridges, its segments corresponding to 717, 179 of the distributor shown in detail in Fig. 7. Relay 6 in operating locks through its left hand winding and left armature contact to battery at the inner left alternate contact of relay 5 which relay it will be recalled was operated and looked under control of relay 13 at the time the trunk was seized.

Relay 3 is of a sulhciently high resistance so that relay lwhich is marginal did not operate in series with it, and relay 2, when the p ug Was i ert in ja ,J- W en 1 lay 6 operates however, resistance-A is conne edn un t el y 3 er by c usi LlZ fiQ L B han i t e sist n e of h circuit of relay 1 to enable it to operate thereby lighting lamp L to indicateto the A operator that the connection has been completed to theline of the called subscriber but that the receiyer is on the hoo'lr.

' Relay 6 in operating deenergizes slow-to release relay 7 but this relay, due to its slow character, does not close its right normal I contacts to connect relay 1.0 to lead 125 until after the 120 volt negative pulse has ceased. When relay {7 however is fully released relay 10 is connected to leadl25 and is in readiness to respond to any further impulses of current connected thereto in the ignal e e ving ir ui 6 r Returning to tlie inward end of the trunk: After el y pe a it s' e e a y gr und s pplie t eueh c n ac s of lay 4, un i r ay 51 has opera e and wi .onlybe released by the operation of super visory relay 62. The operation of relay 50 temp tes t el ir it o relay 5 as o lo s: r u d, c ta s o el y 44. 220, e a t of relay 52, 228 contacts of relay 61, 229,

' conta ts f r y 55, 3 ,.c nte t Q1 ay I 50, winding of relay 52,battery to ground.

Relay 2, n' Op rat ng n t s 9 acting relay 59 to the alternate contacts of relay 62. Belay 59 does not operate at this ti ow e s n e re ay 62. i n y ep ratedk r,

The unctiee c t e by h p rati n of relays 52 and 49 will be later described in 0011 16 5 911 W h t fla ng y t h eperation o ay 49 compl es he circuit o frelay as follows: ground, conest of r ay 4 6, Co tacts o relay 215 winding of relay 5 3 contacts of relay 39,

battery to I ground.

So. long as relay 49 remains operated operation ofrelay 53 has no efiect upon the circuit but as soon as relay 49 releases a short circuit is removed from the winding of re lay 54 which then operates in series with relay 53. Relays 54 and 53 are'locked to ground tlircugh a back contact of relay 61,

the purpose fwhich will be described later. hen the signal sent over the distributor ated again.

signaling circuit has been transmitted to the A or outward position, where it operates relay 6, etc., as previously described, a momentary ground connection is made with conductor 224 when the transmitting distributor 728 completes its revolution in the same manner that ground was connected to conductor 33 to operate relay 8 as previously described. This ground on conductor 224 operates relay 55 for a short interval of time. The operation ofrelay 55 will release relay 49 and leave it in a position to transmit another signal to the signal storing circuit.

The release of relay 49 causes the operation or" relay 54 in the manner previously described' The operation of relay 54 conipletes the following circuit; ground, contacts of relay 52, 204, contacts of relay 54, 203, contacts of relay 60, 205, left hand windin of relay 56, 206, contacts of relay 57,

20!, pick up interrupter 500 to battery.

Relay 56 locks up through its'second winding to battery through contacts of relays 39 and 57. I v

The operation of relay 56 prepares a circuit for operating relay 57 when relay. 52 is released and also connects the winding of relay 58 to ground through interrupter 60:0.

"The operation of rela'y 56 also opens the C1ICu 1l2 of relay 60 causing it to release, the

purpose pf which will be described later.

V The circuit of relay 58 is completed as follows: ground, interrupter 600, contactsof relay51, 226, contacts of relay 56, 227, wind- 6 111g of relay 58, battery to ground. The

operation of relay'58 connects ringing current to the tip and. ring conductors of the outgoing end of the trunk to the called subscribers line.

Ringing. current will be applied to the subscribers line in two second intervals, such intervals being regulated by the cornmutator of interrupter v660.

Whenthe called party removes his receiver the supervisory relay 62 operates. The operation of this relay opensthe circuit of relay 50 which in turn opens the circuit of relay 52. Relay 59 operates momentarily but has no effect upon the circuit. The release of relay 52 causes the operation of relay 57 by completing ground to the following path: ground, contacts of relay 44, 220, contacts of relay 62, 219, contacts of relay 52, contacts of relay 54, contacts of relay 56,

left hand winding of relay 57, contacts of from the ringing interrupter and opens the The release operating circuit forrelay 57. of relay 56 causes relay 60't-o become oper- The release of relay 52 connects ground to signal control circuit (Fig. 7) and es tab lishes a conditionwhich results in the transrelay 61 as follows: ground, contacts of relay 44, 220, contacts of relay 62, 219, contacts of relay 52, contacts of relay 54, 211, contacts ofrelay 29, 210, winding'of relay 61, 234, contacts of relay 55, batteryto ground.

- The operation of relay 61 connects ground to conductors 222 andf223 extending to the mitting distributor 728 sending over conductor 727 two "current pulses whlch cause the receiying distributor 622 and the signal receiving circuit 621 to connect a mom'entary' pulse 01 positive-polarity volt cur rent to conductor which, due to the con nection of the windings of relay 6, causes this relay to release. The reason for this is that the locking current flowing inthe left winding of relay '6 is of negative polarity and as the connection of'the right hand winding to conductor 125 is such that a negative pulse incoming thereover will aid the locking circuit, then a positive pulse coming in over the conductor 125 will oppose the effect of locking circuit and cause the relay to release. 7 i .f

' The 'releaseof relay 6 removes the shunt from relay 3 and thereby'increases the resistance in the circuit of relay '1 to such a point thatit will notholdoperated. The" release of relay 1 o ens the circuit or lamp L which becomes c ark and signifies to, the

A operator that the called'subscriber has responded.

. The operation of relay jalsoreleases relays 53 and 54.

lVhenthe receiver of the called subscriber J is removed and the signalindicating thatfact has been transmitted over the distribu-;'

tor signaling circuitj a short Liinpuls'e of g1'OL1I1Cl 1S applied ,to conductor 1224 at the transmitting distributor circuit, in the same manner as previously described in connection with the outward end of the circuit, which operates relay 55 momentarily. The operation of relay 55 opens the circuit of relay 61 and leaves the circuitin'a' condition so that other signals maybe transmitted to the signal storing circuit.-

Should the called subscriber replace the. receiver onthe switchhook before the con,-

nection is taken down, the outward open.

ator may recall hi nii" desired by ringing on the circuitiin the usual manner. H

'lVhen the outward-operator re-rings, the

ringing current flowing over conductors and 131 passes through the winding of relay "'11 which is in series withcondenser R and retardation coil C. (so

The ringing current"operates relay 11 which in turn completesthe circuit of relay 121 as follows: ground, contacts of relay '11, 123, winding of relay 12, relay 4, battery to ground;-

hen relay 12 operates it locks to ground ,which locks up through itsleft hand windbatte'ry togrou-nd.

124, contacts of through contactsoit' relay 3. -Whenthe oporator ceases ringing, relay 11 releases-and closes the circu t of relay; 4 as follows:

1 ground, contacts of relay 11, contacts of relay 12, contacts of relay 13, 107, winding of relay 108, contacts of 'relay 8 battery to fground. 'Relay 4 locks up again overi'ts as was used to light thelainp'Q' when the call was initiated, therefore the Tea-ring iinpulse 1s received at the inward end. of the trunk as a second nnpulse of negative 120 volt battery current overconductor 125.

When this second inipulse of negative 120' which permits theoperation of relay 40 yolt' current is transmitted overconductor 225 relays 39 'ancl160 are already operated ing over the following-path: ground, con-"j tacts of relay 60', 181, winding of relay 40,,

Contacts ofrelay 40, contacts of relay 39,

'lheoperationotrel ay 40 opens the cir cult of and causes the release of relay 57 and completes. the circuit of relay56 as follows:

ground, contacts of relay- 40, 203, contacts of i 'Jr'ela'y 60, 205, winding of relay 56; 206, con- 'ta'cts of relay 57, 207,"interrupter 500" to ground;

The operation of relay connects the ringing control lead to the winding-of relay 7 -58 causing; it to operate as previously do 1' scribed. f The operation of'relay: 56*also opens the circuit of and causes the release of relay 60, which in turn opens thecircuit of and causes the release of relay '40; ,1 I

l hezoperation of relay 58 connects ring v ing currentto theftrunk and if the' called subscribers receiveris on the switchhoolr,

switthhook the operation of relay 58 will release relay 62 wh ch will allow relays 49 and 50 to be operated from ground through the 'the ringing continues until the receiver is renioved fron'i the hook or until'the' connection is released. v r

If the called sub'scribei"s receiver is'ofi the contacts of relay 44 as previously described The operation of relay 49 willfconne'ct ground toconductor 222'to' "transmit-a signalto-the outward position Where-it will light lainpL for a shortperiodQ Thissignal is trans'niittedlin, exactlythesaineanain nerias previously describedi Howevenfwheu relay 58 releases on the firstbrealro'f intcr- 'rupter 600 and relay 62- operates relay (31 Y operates to transinit a signal to the outward position which 'ezgtinguishes lanip lithus indicating that the receiver is off the hookgf,

llO v I so ' signal storin The transmission of this signal is the same as has been'previously described. The operation of relay 62 causes the operation of relay by closing the following path: ground, contacts of relay 44, 220, contacts of relay 62, 219, contacts of relay 52, contacts of relay 54, 211, contacts of relay 56, 212, left hand winding ot relay 5?, contacts of relay 39, battery to ground. The operation of relay 47 opens the circuit of relay 56 which upon restoring disconnects the ringing' control conductor from the winding oi? relay 58 thus causing ringing current to be discontinued. I

lVhen the ringing signal which was established in the signal storing circuit by the.

ground applied to conductor 121 has been transmitted over the distributor signaling circuit, an impulse of ground is furnishec from the signalcircuit to the outward trunt; circuit. over conductor 122 as has been pre viously described, resulting in the operation of relay 8, and in turn the release of relay 4. The release of relay 4 removes ground from conductor 121 and prevents any more signals being transmitted to the 1,, circuit until a further change has been made in the outward trunk circuit. l/Vhenthe called subscriber flashes, that is moves his'switchhook up and down to attract the A o'perators attention, the first downward movement releasesrelay 62. Re lay 62 in releasing closes at its baclr contact a parallel circuit for the operation of relays 5 0 and 49 which can be traced from ground at the inner alternate contact of relay 44, conductor 220, contact of relay 62, 228, outer normal contacts of relay 61, 229, right ormal contacts of relay 55, 231, then the cir it branches to the right through the right hand gizing circuit for relay 52 which can be traced from battery, winding of 52, left alternate contact of relay 50, 231, right normal contacts of relay 55, 229, outer right contact of relay 61, 228, normal contacts of relay 62, 220, and alternate contacts of relay 44 to ground.

Relay 50 also locks itself over its right alternate contact, 230, normal contact of re- 216thereby causing theoperation of relay 53in a circuit which can be traced over the inner right normal contacts of relay 54,

215, winding of relay 53, conductor 170,

again light, as before described when the called line was plugged into. It the called subscriber should not again release the switchhook lamp L would remain lighted as an indication that the called subscriber has hung up.

After the transmitting distributor 728 has sent out the signal pulse above mentioned a momentary ground is applied to conductor 224 as previously described which causes relay 55 to energize for a sutlicient period to permit relay 49 to release which, relay was looked under control of relay 55. When relay 49 releases it permits the operation of relay 54 in series with relay 53by removing the shunt from around relay 54. The ener gizing circuit of these two relays, 53 and 54, can now be traced from battery, contact of relay 39, 170, winding and. alternate con tact of relay 53, 214, winding of relay 54, 213;, and to ground at the contactotrelay 61.

,7 Now, if the subscriber quickly raises his switchhoolr and depresses it again the tollowing occurs:-

When the switchhook is raised supervisory relay 62 operates which in turn releases relay 50 and energizes relay 59, the circuit of which can be traced from battery winding of relay 59,221, right alternate contacts of relay 52, which relay isslow to re v lease, 219, actuate contacts of relay 62, 220

and to ground over contacts of relay 44.

Relays 50 and 52 are slow to release and will hold operated during the, flashing interval.

lVhen the switchhoolr is once more depressed relay 62 deenergizes which again energizes relay 50 whichin turn again locks up under control of relay 62.

The release 01 relay 62 also operates relay 49 whiclragain transmits a pulse of cur rent over the signaling circuit which results in the application ota second pulse of negative 120 volt circuit to conductor 125 which causes relay 10, which was connected to conductor 125 when relay 7 released after the first pulse to operate. Relay 10', due to the connection of its windings, locks up at its leftcontacts to negative battery, this holding circuit being completed at the'alternate contacts of relay 3.

i The Operation-Of relay. 1 transfers the low:

resistance circuit for operatingrelay '1 from steady ground at the normal contact o'f relay to. ground in series With flashing interrup'-' ter I, thereby flashing the lamp L, which flashing continues under control ,ofthe in-l terrupter until the" called subscriber stops Working hisswitchhook.

-When relay l9 operated at this time, due to the operated con'ditionof relay 54, it caused the operationof relay 51 the circuit I I Relay 51,? in operating, looks at itsiinner left alternate'contact' under control of relay .61 'in an obvious circuit. "Relay 5 1,,inat- .tracting its outer 'leftrarmature transfers 1 thelocking circuit 'ofr-elay' 50 from control by relay 62 to relay '6lthereby preventing -=relay 50 from releasing when relay 62;"again -..o]; erates..i: ;Afi8'1 thecompletion of the second pulse by transmitting distributor 728,. just] dc scribed, the usual momentary ground is applied to conductorv 224 Whichinomentari-ly i energizes relay 55Wlll0l1 causes the release,- of relay 49.. V- 1-- Q 'Due to the slovv, character of-relays" 52f and 59, further flashing: by "the subscriber; -will not cause these relays to-release'anchas relay'50 is locked up independent "of relay 62, relay 49 cannot be r e-energized to "cause; the transmission offanypfurther signalsg 'VVith relay -52 operated the release of relay"- :62 cannot operate relay 61 to cause a signal to be transmitted to the outward end of the. trunk to indicate'that the receiverof the called subscriber is off the switchhook.

When the called subscriber stops flash-1,; ing'a-ndallows hisreceiver to remain off the 'SW llZClIhOO lQ'IElQ-YYGQ energizes and remains energized,-. so long-'asthe receiver is otfthe,

" switchhooln l Vhen relay 52 finally releases ground is" connected to the inding of relay I Gland a signal is transmitted over tlie'distributor circuit similar to the signal which indicates that'the" called subscriber has an swerea.

This'signal when received at the outward end of the trunk ,linereleases the tact of relay'55.wvincling of re'lay 61', 210,?

,fiashing relays and extinguishes lamp L' thereby indicating that the receiver of the called subscriber is oii the'sivitchhook.

The energizing circuit for relay 61 can be traced from battery,'outer left'norinal' conouterleft normal contacts of relay 49, 211,

left alternate contact of relay 54;, right normal contacts of relay 52, 219, alternate contacts of relay 62, 220 and 4% to ground; 1

- Ifthe called subscriber stops fiashingand:g then replaces the receiveron the switchhoolr na'te contacts of relay 54,211, inal contacts of relay 49,?3 ndingfo'f relay 3 55 toy-battery?" Belay. 61': in, operating c' onnects ground to; leads 222 a11 22aa rsty causing ajsignalf; to be "transmitted a as beioreflto ext 'iin'g'g'uislr contact of relay then rclay'62 releases,Which-Will release re-f lay 59 bum-cl 5 2 Wvill remain. cpemtc 1. "Under these conditions, ground ivill l'iecon- Y nected to the winding. of relay 61at the .backjcontacts of relay 59 in thefollovving" circuit ground,normalcontactspf re1ay 59, iright 1" ternate contacts of relay 51,j218, left alter- Z outer; left nor and a sare lamp L; "Hoiveveras,soon asthis signal is transmitted due to the njlonientary operation so P and a .second'fsignal immediatelysetlup and transmitted tothe outward positionj o igh't lamp L to indicate,thatKthev-recjeiiier' of-thecalledfsubsoriber"isfon"the switchhook- V 1 hen-the, outward"operator disconnects from the trunk Jeiitending Zto'ithe' line or a the called subscriber; has replacedihis i receiver contactsofrelay V I Winding 0'if -I6layf13; contacts Of-r'elayS, bat-r conductors 120andl21, causing the disc'onneet; signal ato belsent toathe outwardgend leased whereupon relaye9'jvillg beflenergined 1 called subscriberrelayf 3is lcleasedi Ifthe Q j a i:

.te'ry to ground. f Theifloperation of'ii lay lii 'opens thex rcu t ofirelay -wand. connectsf ground to theslgnal 'stor ng jcircnlt overff 15 1 I otthe t ru'nl:. j This'signal is received at lthe inward. end of 'the ftminklfcir'cuit as an inn-1:;

pulse rgofipositi've "1.20 volt current over: con

ductor 2-25 which.ireleasesrelay 39. The-r s. v I lease of this relay-"completesIthecircuit'ot I relay 63 asjfolloyvs z gronnd battery, contacts of relay 39, 240, c on'tacts'ofrelay;63,winding;

of relay. 63, contacts {of 'relayflt l fto ground. The. operation ofr-elay r63jcompletes the 'cir-o; .cuitof lampQ; as follows: groundjbattery,

contacts of rel'ayw63, 1 94,, contacts' oiifrelay e6, 178,.ilamp' Qyto' ground; Belay 39lalso r a es a The 'hghting'of this lamp serves to give a through its own contacts and/transfgr'sthe "Winding of relay46 from battery through 1; the contacts ofrelay G3to battery through fcontactsofr'elay 39. -The operation of relay '63 also opensthe busy test lead extending" 'from v the tip of the plug to tlie operatorfs telephone set. z

. 'When' thexdisconnect is setup by 1151 Y disconnect signal to "the'invvard.operator,. WVhen relay 63 operates, it looks to battery the signal storing circuit at the'l' dutivardend I and 1s transmitted lJQViLlIG- ClIStZLIliD 'OI inward "end ,ofthe trunk over the distributor signal a system, a ground n'npulse as received from the signal storin g.circuitoyerconductor 122 resulting in the operationetrelay Send the eompleted' through the left handminding consequent release of relay 13 The rel-ease 'oi this relay to batteryo-ver ther'innereright of relay 13 disconnectsground'from conduc alternate contacts ot' relay 48, middle normal tor-e120. and 121 and prevents any -further contacts of relay 47 ,"-conductor-172; inner SYsignals"being transmitted: to the signal right-normal eontacts otrelay 46, 1715.170

storing'circuit until'i'urther changes have -andcontacts of relay i39. V "been ni'ade inthe'outward trunkcircuit. 7 "Duet'o' the directional connection ofLthe After'th'e' inward operator receives th'e'dis two windings of -re1ay- 4% thewcompletion' of 'connectrsignal she-removes the plu'g fro-mtl1etl1e circuit through the left- 1 hand-Wihding it" jack of'the' called linecausingthe release ofwill cause 'this'relay to release; '[lheurelease 1 relayf 44 which in turn causes the release 0t of relay '42 disconnects :ground. from vicon- L relays 63'and46, leaving the inward end oi "-d uctoi- 189 extending to theucall-=..sequence the-trunkcircuitin its normal position t-0*= 'circui t thei'eby cauSing relayQZ to-irelease. receivea'nothercall. ltelay72 in-releasing?-disconnectsground 15- Ifythe-inwardoperator is slow in taking trom conductor 182 thus releasing relay: 48

1 doWnthe connection the outward operator which disconnects the operators telephone 'may select 'th e'tr unli line for-anothereall= -=set fro1 i'i the-trunkilinel The irelease'? of re "before'the connection for the first call is lay 49} also 'disconnects:conductor 196.;trom' itaken down. battery, which was supplied at: theiileft 2") 7 """W:hen?';the 'outward'operator places -the' alteriiate contacts oflthisrelay. I 1

Plug Ofthe cord circuit into the trunk jack, -Relay 7S operated in series:'Withuthefleft ajsig'nal istransmitted o er*-'theg signaling lrand'winding of relay 42 butireleases when "circuit which isreceived at theinward end relay 42 releases. \Vhen :relay378 operates a of'the" trunk asan impulse ofneggatiye 120 it connects ground at its contact's'tog,=cause 25 voltibattery over condu'ctor 225." This in1'- 1 the operation Of relay-TS.Wltichirelayinturn' 0 1 {pulse "causes rela jy 39 to' operate"and-lock-preparesa circuitJi or thenoperation of re- "'"'"up as previously"described. The operation lay 7? which can be traced:iromibattery, iofzfthisrelay'releases relay 46 and operates winding of relay [7 9,; alternate contacts of relays 60, 41f andf42-rand 'maintains the relay 7 9, conductor 197, windingofirelay 7T, signal la1np Q'lightedc I I conductor 199 and left hand contactsof: re The circuit operates as previously; de-- lease key 700 to ground-u Re1ay.7;7 ,ehoWever, I scribed and the'telephoneset of the inward does'hot operate atthi's time as itis shunted f1 operator Fig. 4 is'oonected to thetrunk line by ground atthe' alter ate Econtacts oi irelay as-soon as the operator is free to receiveth' YSJW Vhen relay TSJreleases uponrthe release 1 35 eall" whereupon the signallamp Q is caused of relay 42 it removes the ground which to flash as before. The inward operator, previously shunted relay.- TZnandxthiswelay howeyer, canhot release her telephone set then operates in therpreviously described from the'line untilshedisconnects the trunk circuit in series with relay'79. iTheoperaf line-from'thesubscribers'line by Withdrawtion of relay 77 removesground"fronticon-.

' 4 0 ingthe plug from the jack or unless she op- -ductor-196- thus preuentingzanore than-:oiie

erate's th'eiemergency release key to be-later trunlrline releasing at: once from the opdescribed; T his withdrawalreleases relay eratoistelephone set even: though the co1n- 44"Which in turnieleases'relay 635 The remen release" key should be held operated. v lease of relay 63 restores the operatorsbusy Relays 79 and77wwill beuheld operated as 45' "test lead to theitipof the} plug and con-- -longas release key 700 is-operated." I 5 i nectsbattery tothe Winding of relay-{46; The inward operator thenconnects the trunk V V line to the Wantedline and releases 'her Should the outward operator disconnect telephone set as previously described. oer-ore the. called subscriber has-:l ungeup, 50 A release key 700 common to each op-' for the purpose of changingicords ;for. er? 'eratorfsposition is'provided to enable the-ample, there Will be a delay of about "2 w inward operator to release her telephone set seconds before the disconnectsignal to the from a"'trunl if desired Without-requiring 'ii'iward operator is transmitted,andvthere- 'hertoplug thetrunk into'an outgoing-'subfor the trunlcwill lie-guarded at theioutyscribers1linejack] This circuit is common going end for-this shortrinterval thus ,pre to all of the trunk circuits towhiclr an'op- Venting another loperz tor from-seizing the 1 eratorjs' telephone set may beconnected. trunk during the'changii'igoperationp This The release key 700 is non-locking and "delay interval is accomplished,by -means of wvhen operated removes ground from cona 'serie-sor chain: Of-fS'lOW IGlQELSGwIGlBJYS.

60 ductor. 225. and connects, groundthrough These relays are con'imon to a group of v thebaclrcontacts of relay 77 and the (Wind fifteen trunks. f fling of rela'y78 over conductor 196 extend If the outward operatorshouldreconnect "j'in'g tothezarmature of relay 42E Relay 42 Within the 2 2 second period-thedisconnect I .being already energized in-a circuit includ- "signal. is not sent toctheifinward[operator 1mg its "right'hand Winding, a circuit is thus as relay 3 reoperates betorevrelay 1320p- Belay feature to permit chtmg ingco rcis. i

' V 23'11as its circuit completed which is when erates. Thisdel'ay in sending-a disconnect signal to the inward operatoronly occurs when relay 7 is ope'ratedat the time relay 3 is released. WVh'en the A operator dis- 5 connects relay-'3 releases which in turn re leases relay 4. I i 'l/Vith relay 7 -operated the release of relays 3 and tcauses the operation of relay 6 14 the-circuit for which canbetraced from battery, Winding of relay 14, 116, inner right alternate contacts of relay 7-, 115, outer left normal'contacts of relay 4;, outer leftalternatecontacts otrelay 5, 113, and

[normal contacts of relay 3 to groundQ Relay 13 does not operate to ground con- I -ductor 121,-thereby sending asignalipulse to the inward end to light* the" lamp Q.

asga disconnect signal, until the timingcire cult causes ground to be connected to con ZQ'ClHQtOI' 118, unless the 'icalled"subscriber} should 'disconnectjinthe meantime. If this should happen relay '6 operates from nega tivej120 volt current'impulse received over' conductor" 125 causing relay ,TftO- releasei Relay 13' then immediately operates on- 4:, baclcco'ntactof 24L and front contact ofrelay 20, i The operation ofrelay also closes the ;circ'uit*of' stepping magnet 22 I as follows':' ground, contacts of relay 20, .151, contacts of'relay 23, 152, winding of j.1nagnet '22, interrupter contact'sioi magnet 22, resistance 4500,- battery to ground; The

operation of the switch continues untilrelay the wiper associated with the bank con- .tacts O engages} ground. Tl11S 'Cl1 'Cl 1lt &t

' this time will'be as followsz-ground, bat-f 'tery winding' of relay'23,fO, 11'9, contacts' of relay -14, to ground. The operation of relay 23,breaks.thecircuit of the stepping magnet 22 causing the'switch to come to rest W1th the Wipers resting on contacts oi:

'J. The operation of relay 28 completes the v circuit of relay 2 1 as follows: ground, contacts: of relay 20, 151,"con'tacts of relay 23, 1156, contacts of relay 2%, contacts of relay relay 2et, battery to ground. a

The operation of relay'24 opens-the circuit of relay 21. Relay 21in releasing connects battery to onefside of the windings of relays 26, 29, 28, 27 and 25. Y

Y I The operation of relay 24fcause's the cir- "icuit of relay 25 to lie-completed as follows:-

ground, contacts of relay 20, 151 contacts of relay'29 cause the"circuit-ofrelay -26 to 1 f the equipment associated With thetrunk-jack I I I battery through the contacts of relay ,8.

29, cont'actsot'relay 28,"contacts of relay- 2?, contactsflof relay 25, 158, Winding of ofrelay 23-,*1 5 6',-contacts f relays 24, 1'57, I

combination allows the circuit ofrelay 27 to be completed as follows: ground contacts of relay*20, 151, contacts ofrelay'23, I:

156 contacts 'ofrelay 24, 159, contacts of relay 25, 160, Winding. of relay 27Yto battery-through theo'ontacts ofrelay 211 The -operation-"o.relay -27 opensthelcireqfl cuit'ofrelay'25, allowing itto'restore; The 1 I I operation of relay 27; andthe restoration of relay; 25 cause the circuit of relay 28' to be 'closed as'follows:ground, contacts of relay 52 5 20,151, contacts of relay 23, 156-, 'conta'ct s jot relay 24,159, "contacts OrreIa 25',-,con-; I l

'tacts ofrelay 27, 161,winding of relayf28, to battery through the contactsof relay-2'1;

The operationofrelay 28, opens thecirjs The Y V operationifof relay 28, and the restoration ,7 of relay 27 allow s the'i circuit of relay 29,," I

cult of relay 27, allowing it to restore.

to be closed asjfollowsz ground, contacts of relay 2o, 151,?contactsof relay 23,156, cone tacts of relayv 24, 159, contactsaofrelayf25,

contacts of relay27, contacts?ofrelayQ28,

1'62, windinglof relay 29, to batteryjthrough" itlie contacts of relay 21.:

The operation 'oflrel'ay29 .opens th ci cuit ofrelay'28 "causing jit to restorej the; i a

restoration of relay 2 S and :the operation be fclcs'ed "as follows: ground, contac s f relay 20,5151, contacts of relay 23,156, con L I tacts'of'relay 2fl 159,-conta'cts o'f'relay25, contacts'of" relay 27, contacts 'ofr-relayt28,a' contaots ofirelay 29, 163, winding of relay j; 26-to battery; through the -j c ontacts, of

At-this tune the only' 'relays inr th'e timingf I,

circuit "operated are relays 20, 23' and 26,

Xvitlnthis' coinbination the circuitof'relay i "'13 is completed as "follows ground, contacts 1.

of relay 2O,";15 1',". contacts'of relay 23, 156, 9-

contacts of relay .24, 159, contacts of relay :27? 29, Contacts of rela 26,165,- lk O S N of the switch, 118, contacts r of relay 14, 112,"Winding o.re- 1ay .1-3, toj

conductors 117 and 119 causing therelease 120 ofrelays 20, 23 and 26.":

In many instances the timing circuitfwill be released by the trunkcircuitbefore the tuning operation isfcoinplete. When this happens the circuit restores to normalune 2 51 j less ground is connected to; conductors 11 7 1 and ;119'-by sOrne other trunk] circuit.- In. I the lattercasetlie' switch will l unt for the I speed faster than can be handled by the the fiQmnecessary ,to store up these-calls and con regularaorider. l

I :5 rlvlelaysYiand/TG are operated y "other circuit and when it is found ,will start trunk and connects the oper a 'tors telephone the tiining operation overgagain. set to. that particular trunk. i 'yi lh e fact thatrelay 21 is, operated during "After the connection has been established :nlthe liunting period insures that any, of-the, ove gNo. 2 trunlnrelay 73 isireleasedthere- 45 relays. in the chain which inighthave been, byallowing the operationotrelay 75 'by the operated at the. beginning f the, hunting following path: ground, contacts ofrelay period will release andthe full ti nednteryal- 71,-conta c ts o f relay72 contacts ofrelay 78, ,will beriobtai-ned in eachiease. contacts of relay; 74;, 186, winding of r elay 5, cha e y, o erean e h r rat m of r,elay .7 completes the-circuit of relay 43 The callsequencecircuit is arranged to; of trunk NO 15, thereby QmwQfi g he 0pi., connect,y an operators telephone set in suck,eratorstelephone setto that trunk. cessivehorder; to the trunk linesvter ninating' Atfter the establishment ofz the opnneetion at ,l1erposition on which calls arewaiting. thdoperatofis ;te1ephone, setis disconnected m Call segue nce circuit. 7

' 5 It islevid'entthatin a group of trunk lines iron trnnl -Ne.- 15.

which calls are originated,independently, The operat iong of, relay 75 which isthe I ifthatqca-ll waiting signals Tina-y be received at; highestjnuinbered trunk of this series breaks battery supply extending to! the windinwarda'operator and that some means is ings eta-l1 the. relays 72,; 73, '74, etc in the I series; meet them to the o'peratorls telephoneset in call should originate on one or nore'; of j the ;;other; lower numbered trunks in the ;i' .For simplicity, the call sequence 1 circuit, groupiqlvhen; a connection has been estabas. illustrated, shows; relays forthree trnnks ,lished bet yeen thetrunlgandthe called line, .5. onlyatloneioperators position. .ontherelea-se key ZOO is operated, as previ- Relays 72,173 and 74 are operated by ously described ground is, removed from groundconnected to their windings over c,onductor. 189 andthi i-Lconductors. individual tothe respective which in turn releasesgrelay 75,

trunk .lines;: The battery for relays 72, 73

Rclays 72 73 and 74L is suppliedthroughthebackcontacts theirarrnatures and consequently there is "ofrelays76 and? 5 arranged in series.

The an interval of time between the release of battery supply for. relays 72 73, 7d is fun. each, relay florn 72 73', 74, etc to its r a nished through relay. 75 which is, nuineri l callythe highest. trunk in the group. i )7 time intervalthecalln sequence .cireuit is ground made to operate in the regular; order from connect-ions receiyedwthrough the series ot h 'zfi w dll h 191st j fl kll filllllhe -J..relays 72, 73 and 74 of numerically lower signals oflthe highernumbered trunk lines I ..tr u nks.i Q have beentransniitted. :After thisthe se- Forithe purpose of: illustration we, will; quence' circuit returns toits .nor nal starting assume that calls are originated simultane-, ;position and isready torepeat:theoperae ously on trunks'l, 2 and 15. Underthes'e tion. 1 conditions there will be a groundplaced on each 189 conductor extending from trunks V i 1 2 and 15,; Theseground,conneotionsop- Theemergency transfer circuit is coin- -erate .relays 7 2 73 and 'YlzMThe op eration;m l -E D f he inwaig'dt unks t r n ng of relay 7 2 connects ground over conductor a bnoneiilln'a l op ra ons position. .lThis'cir- 182 tonuinber l trunk circuit, but the opercnitiallows the inward operator to answer Emergency transfer circuit.

I cation of relays-,7?) and 74: at this time dov inel l ly hetr mk l m na i g ....'.not.- change'the circuitconditions so long as her position by pe-ratingflm tea-n1 key X 5.0 relay 72 is operg ted, ,Th peration f r lay associated with ,each trunk. This feature 72 completes thecircui-t of relay L3 as folwill benecessary incase' of trouble in the lows: ..grou11d, contacts ofrrelay-Tl, contacts call sequencecircuit. This circuit is operofirelay 72, conductor 182, winding of reated by neans oli the einerg g'ency transfer 7 lay 43, battery toground; The operation of key 7 29 which when operated, connects relay 43 connects. the operators telephone set toztrunk number 1. l Theop erat ion ofrelay 70V disconnects ground Vhen relay 7 2 'isreleased which will be from conductor-190 therebyipreventing opafter .theOperatOr atthe. inward position -;eration of the call sequence circuit and opens completes the connection then; relay 76 istl1e conducton25Textending to the call seoperated over tl1e,:followingpatha ground, quenceneircuit at theadjacent position and contacts of relay 71, contacts of relay 72, also transfersCQnductor 21l frorn the posicontacts: of relay: 73.;Winding of relay 76,1 tion release :key at the adjacent position to battery togr0 und. The operation of relay" the oneatthe l o1neposition. "Ihe, operation 7 6 completes-the, circuit of relay 43 of No. 2 or" this relay also transfers. conduetor 251 Thisr ve i h lz pera on in C s rele rel y,

nd 74 are slow to release .spectivg relay 76, 75, "etc; Bymeans of this ground tothe-windings of relays and 80.

extending to interrupted battery at peremptory frequency to one corresponding to a busy back frequency. r

' The ope "ation of i'elay SOti'ansfei's con ductors 142, 143 and 254i common to the toll line from conductors extending to the acent operators telephone set and connects them to the home position telephone set.

What is claimed is 5 y 1. In a telephone exchange system, the

I combination of an A operators position, a l

lines extending betweenv said positions, ineanscontrolled by the A operator'for B operatorls position, 'a'plurality of trunk seizing one of said trunk lines, a telephone set associated with the B opei'atoi' spost tion, a signal also associ-ated Withsaid' 13 position, a signaling path common to said plurality of trunk" lines extendi ig b'etn' eeii the A and B operators positions, means controlled over said path for operatingsaidi 1 signal and for causing the coiinectionof the V line'iseized by the A operator.

- erators position, a telephone set at said B B operators' telephone set with the trunk 2. In a telephone exchange system, the combination of an A operatorls position and a B operators position,,a plurality of trunksextendingbetween said positions, a signal lamp for each trunk at said B ope f operators position, a signaling circuitcomtrunks extending between said positions, signal lamp individual to each trunk at said" B operatorsposition, anoperators telephone set at said B position,' a signaling circuit ,coinmonf'to sa d plurality of trunks @extending between said positions, means controlledfrom the A ope ators position for seizing a trunk extending to: the B op- GlfQ tOIiS position, and means controlled. oversaid common-signaling circuit for lighting the signal lamp associated with; theseize,d

' trunk andflfor connecting the B operatoids telephone set therewith;

at. In a telephone exchange system, the

COmblliifl'ilOiI Of an A operatorsposition 7 audit, B operators position, al'pluralityof iposi-tioiisg insaaaa aa when ii: triiirll jack f trunks extending between said positions, said trunks terminatingat the A operators fpo-Y sition in jacks, a signal lamp 'individualjto B operators telephone. set at'sai d B 13161 1, coinino" signaling circuit'iof said pl."rality of minis extending between 'e-idf eacli'trunk at said tB operatorsposition, a;

at the Aopei'atoris position isselectedfor transmitting asignal overtlie common signaling circuit to actuate means to light the" lamp associated with the selected trunk to be lighted and to connect the B operators telephone set'with the selected trunk.

In a telephone excliaiigesystem, the

i combination of an A",0 p rat01"S position and a B operators position,aplurality of trunks extending between said positions,

each trunk terminating 'at the A foperae' tors po'sition'in a jack, a signal associated With each't-runkat'said Bop eratoi"s posi- 'tion, "a *c'o-mmonsignaling circuit for said trunks extending' between said positions,

cord circuit controlled by" the A operator adapted to befassociated' With one of -said trunkacks, means responsive to the assoc-la tion of said cord and jack for transmitting signal over said commoncircuit extending between said positions, to c'auseZtIhe lighting of the lamp associated with the selected trunk and to connecta tone current" to the same trunk; i p a, v i a 6. 111 a telephone exchange -system,-the combination of an A operators position,

a B operators position, a plurality of trunks extending between said positions, an o-perators telephone set. at said B opera tors positiomja common signaling circuit extending betw'eensaid positions, and means controlled J over "saidfcom non signaling circult responsivetojtlie seizure. of an idle one connecting the ope'rators,l telephone set at the B operator s position tothe trunk seized by'th (A77 Ope a I I I, 7:. Inga tele'phone exchange'systeimj the combination of aiifA -operatorsposition a "FBf ioperators position, a plui' 'ality of trunks; extending between said pos tions, a signal ndividual toeach of said trunks at- "of said trunks-by, said-A operator 01"' said B position, an operatorsFtelephone set at said B position, a common signal; 1

I ing circuit extending between said positions, and .means controlled over said common signaling circuit for connecting said telephoneset to a particular one of said trunks 'andi operating the signal associated there- 8; In [a telephone exchange-system, the

COlIlbll lfilZlOli'fOf anA operators positionp a 13" operators position, a' lilui'alityfiolf" trunks extending between saidpositions,an

operators telephone set at said B position,

aicoinn'ion signalling circuit extending be tween said pos tions, and means controlled over sa d," signal ng circuit for "causing 'theany cine ofsaidtrunks.

a telephone s em ers f'pos'it plurality g r, i'iks 3 positions; signal I i exchange ?systein' in I l 

